▎ 摘　　要

Ammonia (NH3) is one of the most extensively produced chemicals worldwide, and it plays an important and indispensable role in the global economy. At present NH3 is mainly produced by the traditional Haber-Bosch process operated at high pressure and temperature, which results in massive energy consumption and carbon dioxide emissions. The electrochemical nitrogen reduction reaction (NRR) can allow the production of NH3 from nitrogen and water under ambient conditions and is regarded as a sustainable alternative to the Haber-Bosch process because of its low energy consumption and limited environmental impact. In this study, using density functional theory calculations, we designed a monovacancy defective graphene (MVG) doped with various nitrogen and phosphorus atoms and a single vanadium atom (VN1-3@MVG and VP1-3@MVG) to be used as electrocatalysts. The results revealed that N- and P-doping are beneficial for N-2 adsorption and activation and can effectively reduce the energy barrier of the NRR, especially for P-doping. Among the synthesized electrocatalysts, double P-doped V@MVG demonstrated the best catalytic activity with a low free energy barrier of 0.43 eV. This paper reports the development of an efficient catalyst for electrochemical NH3 synthesis and provides valuable insights on the design of electrocatalysts with high activity and stability.